1. Field of the Invention
The present invention relates generally to modular ladder assemblies, and more particularly, to a triangulated modular ladder assembly and to various arrangements using one or more of the modular ladder assemblies.
2. Description of the Related Art
The dictionary definition of a ladder is a framework of two long structural members connected at regular intervals by parallel rungs for climbing or descending. The difficulty with such a typical ladder is that it easily becomes unstable. Many accidents occur due to this instability.
U.S. Pat. No. 2,718,346 to Galen discloses a triangulated ladder consisting of two ladder assemblies joined by hinges and a pair of toggle arms. As illustrated in the drawing figures thereof, Galen discloses a ladder comprising a pair of sections each of which include a pair of laterally spaced stiles tapering upwardly to form a wide base and a narrow top rather than ladder assemblies each having parallel stiles.
Furthermore, Galen discloses hinges that are not separable rather than hinges that are separable via an easily removable hinge pin. Still furthermore, as illustrated in FIGS. 4-6 of Galen and stated in the paragraph beginning on line 25 of column 2 thereof, the toggle arms each consist of toggle elements 19 and 20 pivotally secured by means of a bolt or rivet 21 to a substantially U-shaped sheet metal hinge element 22 rather than having rigid members.
Moreover, Galen discloses only a single pair of ladder assemblies rather than coupling the respective ends of the stiles of two or more pairs of ladder assemblies to form a triangulated ladder having a length greater than that of a triangulated ladder formed of a single pair of ladder assemblies. Lastly, Galen discloses fixed length members (that is, toggle arms) rather than adjustable length members (that is, toggle arms) to facilitate adjustment of the angle between the pair of ladder assemblies.
U.S. Pat. No. 5,012,893 to Kraeger discloses a sawhorse having three sets of outwardly folding legs that are held in the open position by three pair is attached braces which are in turn attached to a bar that runs parallel to the beam of the sawhorse. As illustrated in FIG. 1 of Kraeger, the disclosed sawhorse comprises a beam having three unitary legs extending outward therefrom and three movable legs permanently attached thereto by hinges, rather than a pair of ladder assemblies, each ladder assembly consisting of two parallel stiles having a plurality of parallel rungs disposed therebetween.
Furthermore, the members (that is, braces) of Kraeger are foldable, each being formed of two elements having a hinge disposed therebetween, rather than having rigid members.
Still furthermore, Kraeger discloses fixed length members (that is, braces, rather than adjustable length members. Moreover, Kraeger discloses only a single pair of ladder assemblies rather than the use of a coupling arrangement to couple the respective ends of the stiles of two or more pairs of ladder assemblies to form a triangulated ladder having a length greater than that of a triangulated ladder formed of a single pair of ladder assemblies.
U.S. Pat. No. 4,428,456 to Rohde discloses a collapsible lookout tower that is triangular in cross-section and tapers inwardly from the bottom to the top. The tower has an upper and lower section and can be easily and quickly disassembled and the sections nested for easy transportation and storage.
As illustrated in FIG. 1 of Rohde, Rohde discloses a tower in which the upper and lower sections are each formed of three vertical members that taper inwardly from the bottom to the top, rather than a pair of ladder assemblies, each ladder assembly having two parallel stiles.
Furthermore, the three vertical members of each section of Rohde are joined together by horizontal cross members that are bolted to the three vertical members, rather than one stile of one of the ladder assemblies being attached to one stile of the other of the ladder assemblies by means of at least one pair of hinge assemblies, each hinge assembly including an easily removable hinge pin. Lastly, Rohde discloses fixed length members (that is, cross members) rather than adjustable length members (that is, cross members) to facilitate adjustment of the angle between the pair of ladder assemblies.
U.S. Pat. No. 4,478,549 to Stelly et al. discloses a foldable loading ramp consisting of a pair of ladder-like assemblies joined together by a pair of hinges.
Stelly et al. discloses hinges that are not separable rather than hinges that are separable via an easily removable hinge pin.
Furthermore, Stelly et al. discloses only a single pair of ladder assemblies rather than the use of a coupling arrangement to couple the respective ends of the stiles of two or more pairs of ladder assemblies to form a triangulated ladder having a length greater than that of a triangulated ladder formed of a single pair of ladder assemblies.
U.S. Pat. No. 1,466,757 to Riemer discloses a folding ladder having a pair of ladder assemblies that are permanently joined together by a pair of hinges. Riemer discloses hinges that are not separable rather than hinges that are separable via an easily removable hinge pin.
Furthermore, Riemer discloses the use of a single platform to join the pair of ladder assemblies rather than a pair of ladder assemblies being joined by at least one pair of rigid members to form a triangulated ladder. Moreover, Riemer discloses only a single pair of ladder assemblies rather than the use of a coupling arrangement to couple the respective ends of the stiles of two or more pairs of ladder assemblies to form a triangulated ladder having a length greater than that of a triangulated ladder formed of a single pair of ladder assemblies.
U.S. Pat. Nos. 763,757, 830,485, and 965,712 to Hopkins, Norton, and Holdridge, respectively, each disclosed other ladder arrangements that are not as pertinent as the patents discussed in detail above.